The temperature of operating rooms is usually stabilized at 20° C. The patient is stripped of clothing or is covered only partly by means of a light surgical cover during the procedure. The patient is fully exposed in the area of the actual region of surgery. Additional heat losses may develop during major abdominal surgery due to the larger area and due to the heat of evaporation of the exposed organs. Patients therefore cool down without suitable countermeasures during the surgery, doing so approximately by 1° C. per hour in the first 3 hours. Cooling begins already when the patients leave the heating bed and are prepared for the surgery.
Thermotherapy measures, which shall maintain the body temperature at a preset level or shall bring it to a preset level are used to prevent the cooling and above all undercooling (hypothermia) of the patient. Only few patients are kept warm by additional thermotherapy devices during the surgery even now because of lack of awareness of the problem, which is frequently associated with an unplanned cooling and may lead to considerable health consequences for the patient and to economic losses to the hospital.
The extent to which the particular patient loses temperature and how intensive the counteracting heat supply measures must be are nevertheless unknown.